Steel sheet for two-piece can and manufacturing method therefor

Abstract

A steel sheet for a two-piece can, the steel sheet includes: by mass %, C: 0.010% or more and less than 0.050%; Si: 0.04% or less; Mn: 0.10% or more and less than 0.40%; P: 0.02% or less; S:0.020% or less; Al: more than 0.030% and 0.100% or less; N: 0.0005% or more and less than 0.0030%; B: 0.0005% to 0.0030%; and balance Fe and inevitable impurities, wherein an amount of N that is present as BN and a whole amount of N satisfy the following expression (1):[N as BN]/[N]>0.5  (1),where N as BN represents the amount of N that is present as BN, and N represents the whole amount of N, tensile strength is 420 MPa to 540 MPa, elongation is 5% or more, yield elongation is 3% or less, and Δr is −0.50 to 0.10.

The invention claimed is: 
     
       1. A steel sheet for a two-piece can, the steel sheet comprising: by mass %, C: 0.010% or more and less than 0.050%; Si: 0.04% or less; Mn: 0.10% or more and less than 0.40%; P: 0.02% or less; S:0.020% or less; Al: more than 0.03% and 0.100% or less; N: 0.0005% or more and less than 0.0030%; B: 0.0005% to 0.0030%; and balance Fe and inevitable impurities, wherein
 an amount of N that is present as BN and a whole amount of N satisfy the following expression (1):
   1.0≥[N as BN]/[N]>0.5  (1),
 
 
 where N as BN represents the amount of N that is present as BN, and N represents the whole amount of N, 
 a tensile strength is 420 MPa to 540 MPa, 
 an elongation is 5% or more, 
 a yield elongation is 3% or less, and 
 a Δr is −0.50 to 0.10. 
 
     
     
       2. The steel sheet for a two-piece can according to  claim 1 , further comprising: a film laminated layer having a thickness of 5 μm to 40 μm on both sides of the steel sheet or on a single side of the steel sheet. 
     
     
       3. The steel sheet for a two-piece can according to  claim 1 , wherein the steel sheet comprises, by mass %, C: 0.010% or more and less than 0.020%. 
     
     
       4. A method of manufacturing the steel sheet according to  claim 1 , the method comprising:
 heating a slab at a heating temperature of 1,100° C. or higher; 
 hot-rolling, under the condition of a hot-rolling finish temperature of 820° C. to 920° C., the slab after the heating; 
 coiling, at a coiling temperature of 600° C. to 70° C., a hot-rolled sheet obtained by the hot-rolling; 
 pickling the hot-rolled sheet after the coiling; 
 cold-rolling the hot-rolled sheet under the condition of a rolling reduction ratio of 85% or more after the pickling; 
 annealing, under the condition of an annealing temperature of 650° C. to 750° C., a cold-rolled sheet obtained by the cold-rolling; and 
 rolling, under the condition of a rolling reduction ratio of 5% to 20%, an annealed sheet obtained by the continuous annealing. 
 
     
     
       5. A method of manufacturing the steel sheet according to  claim 1 , the method comprising:
 heating a slab at a heating temperature of 1,100° C. or higher; 
 hot-rolling, under the condition of a hot-rolling finish temperature of 820° C. to 920° C., the slab after the heating; 
 coiling, at a coiling temperature of 600° C. to 700° C., a hot-rolled sheet obtained by the hot-rolling; 
 pickling the hot-rolled sheet after the coiling; 
 cold-rolling the hot-rolled sheet under the condition of a rolling reduction ratio of 85% or more after the pickling; 
 annealing, under the condition of an annealing temperature of 650° C. to 750° C., a cold-rolled sheet obtained by the cold-rolling and performing an over-aging treatment where a retention time in a temperature range of 380° C. to 500° C. is 30s or more; and 
 rolling, under the condition of a rolling reduction ratio of 5% to 20% an annealed sheet obtained by the continuous annealing step. 
 
     
     
       6. The method of manufacturing the steel sheet according to  claim 4 , the method further comprising:
 forming a film laminated layer having a thickness of 5 μm to 40 μm on both sides of the steel sheet or on a single side of the steel sheet. 
 
     
     
       7. The method of manufacturing the steel sheet according to  claim 5 , the method further comprising:
 forming a film laminated layer having a thickness of 5 μm to 40 μm on both sides of the steel sheet or on a single side of the steel sheet.